Screaming Trees

When an eerie sound is heard on the wind, there is good chance there is what is known as a screaming tree close by.
Screaming trees are the remains of corpse trees after the mushroom colony dies off and the flesh has been either eaten or rotted away, leaving behind it's calcium based support structure. This skeleton is similar in structure to that of a dead joshua tree: hollow with various sized holes 'woven' into it.  It's these holes that are the source of the effect that give the tree it's name:  they produce sound when the wind blows through them.
The sound produced more often than not resembles that of many voices screaming in agony.  This, in addition to the knowledge these trees only develop in the presence of a lot of death, lead many to believe the sound is a sign of ill omen.
Thankfully, as in life, the structure is not very strong and is quickly destroyed either by the elements or directly by animal life.